It has been estimated that as many as 30,000 unmanned aerial vehicles will be flying in America's skies by 2020. UAVs are being manufactured in over 70 countries around the world. 23 countries have developed or are developing armed UAVs and/or UASs.
The Federal Aviation Administration (FAA) has granted 24 licenses to commercial UAV operators as of Feb. 3, 2015. Over 300 others have applied so far for such licenses. Individual operators may freely fly UAVs for personal use and enjoyment (non-commercial use). The following proposed rules have been developed for small UAV by the Federal Aviation Administration (FAA) on Feb. 23, 2015 for public commenting:
Operational Limitations:
                Unmanned aircraft must weigh less than 55 lbs. (25 kg).        Visual line-of-sight (VLOS) only; the unmanned aircraft must remain within VLOS of the operator or visual observer.        At all times the small unmanned aircraft must remain close enough to the operator for the operator to be capable of seeing the aircraft with vision unaided by any device other than corrective lenses.        Small unmanned aircraft may not operate over any persons not directly involved in the operation.        Daylight-only operations (official sunrise to official sunset, local time).        Must yield right-of-way to other aircraft, manned or unmanned.        May use visual observer (VO) but not required.        First-person view camera cannot satisfy “see-and-avoid” requirement but can be used as long as requirement is satisfied in other ways.        Maximum airspeed of 100 mph (87 knots).        Maximum altitude of 500 feet above ground level.        Minimum weather visibility of 3 miles from control station.        No operations are allowed in Class A (18,000 feet & above) airspace.        Operations in Class B, C, D and E airspace are allowed with the required Air Traffic Control (ATC) permission.        Operations in Class G airspace are allowed without ATC permission        No person may act as an operator or VO for more than one unmanned aircraft operation at one time.        No careless or reckless operations.        Requires preflight inspection by the operator.        A person may not operate a small unmanned aircraft if he or she knows or has reason to know of any physical or mental condition that would interfere with the safe operation of a small UAV.        Proposes a micro UAV option that would allow operations in Class G airspace, over people not involved in the operation, provided the operator certifies he or she has the requisite aeronautical knowledge to perform the operation.Operator Certification and Responsibilities:        Pass an initial aeronautical knowledge test at an FAA-approved knowledge testing center.        Be vetted by the Transportation Security Administration.        Obtain an unmanned aircraft operator certificate with a small UAV rating (like existing pilot airman certificates, never expires).        Pass a recurrent aeronautical knowledge test every 24 months.        Be at least 17 years old.        Make available to the FAA, upon request, the small UAV for inspection or testing, and any associated documents/records required to be kept under the proposed rule.        Report an accident to the FAA within 10 days of any operation that results in injury or property damage.        Conduct a preflight inspection, to include specific aircraft and control station systems checks, to ensure the small UAV is safe for operation.        
In Jun. 21, 2016, the FAA released a further “Summary of Small Unmanned Aircraft Rules (Part 107). An excerpt of these rules are as follows:                Unmanned aircraft must weigh less than 55 lbs. (25 kg).        Visual line-of-sight (VLOS) only; the unmanned aircraft must remain within VLOS of the remote pilot in command and the person manipulating the flight controls of the small UAS. Alternatively, the unmanned aircraft must remain within VLOS of the visual observer.        At all times the small unmanned aircraft must remain close enough to the remote pilot in command and the person manipulating the flight controls of the small UAS for those people to be capable of seeing the aircraft with vision unaided by any device other than corrective lenses.        Small unmanned aircraft may not operate over any persons not directly participating in the operation, not under a covered structure, and not inside a covered stationary vehicle.        Daylight-only operations, or civil twilight (30 minutes before official sunrise to 30 minutes after official sunset, local time) with appropriate anti-collision lighting.        Must yield right of way to other aircraft.        May use visual observer (VO) but not required.        First-person view camera cannot satisfy “see-and-avoid” requirement but can be used as long as requirement is satisfied in other ways.        Maximum groundspeed of 100 mph (87 knots).        Maximum altitude of 400 feet above ground level (AGL) or, if higher than 400 feet AGL, remain within 400 feet of a structure.        Minimum weather visibility of 3 miles from control station.        Operations in Class B, C, D and E airspace are allowed with the required ATC permission.        Operations in Class G airspace are allowed without ATC permission.        No person may act as a remote pilot in command or VO for more than one unmanned aircraft operation at one time.        No operations from a moving aircraft.        No operations from a moving vehicle unless the operation is over a sparsely populated area.        No careless or reckless operations.        No carriage of hazardous materials.        
The FAA UAV rules will be effective Aug. 29, 2016.
Present UAV technologies have certain deficiencies, as follows.
UAVs technology offers significant benefits to society in that UAVs can be flown economically, and in areas not suitable for larger aircraft. However, UAVs should not be flown into some areas, such as airports, where a collision can result in loss of human life or valuable properties. A UAV drawn into an aircraft engine can cause a total disaster to the aircraft. Moreover, since UAVs are capable of deploying explosives, chemical agents, and operating cameras to record information that may be regarded as private, UAVs can invade an endless variety of areas that could be regarded as illegal, or a breach of privacy, or create vulnerability to destruction of property. UAVs can be used to smuggle contraband and weapons across national borders, into prisons, and capture proprietary video of copyright sport events.
Private industry is addressing at least some, but not all, of these concerns. One such company, No Fly Zone, offers a database containing GPS coordinates of areas that UAV operators can help fill with information. The database is then sent to UAV manufacturers, who implement the database and provide restrictions on where the UAV can fly. It may be possible that UAV manufacturers can add or remove features without UAV owner knowledge. Presumably UAV owners would not be allowed to modify or bypass the “No fly Zone” capability, which may be considered a type of UAV digital rights management.
One UAV manufacturer, DJI of Hong Kong, has agreed to comply with the FAA's Notice to Airmen (NOTAM) 0/8326, which restricts unmanned flight around the Washington, D.C. area, 10,000 other airports, and prevents flight across national borders. Although the U.S. President has requested better federal regulations, it is likely that technology may find a way to defeat regulations.
In the US all airspace outside of a building is administered by the FAA. Additionally operations within a building, such as a stadium, are to a lesser extent controlled by the FAA when operations potentially affecting public safety are involved, such as flying over populated areas. FAA requirements generally are quite similar to International Civil Aviation Organization (ICAO) international standards.
Flight Rules and Weather Conditions
Weather is a significant factor in aircraft operations. Weather conditions determine the flight rules under which aircraft can operate, and can also affect aircraft separation (physical distance between aircraft).
Aircraft are separated from each other to ensure safety of flight. The required separation varies depending on aircraft type, weather, and flight rules. Aircraft separation requirements can increase during poor weather conditions, since it is more difficult for a pilot to see and/or detect other aircraft. Increased aircraft separation can reduce airport capacity, since fewer aircraft can use an airport during a given time interval. Conversely, reduced aircraft separation can increase airport capacity, since more aircraft can use an airport during a given time interval.
Aircraft operate under two distinct categories of operational flight rules: visual flight rules (VFR) and instrument flight rules (IFR). These flight rules are linked to the two categories of weather conditions: visual meteorological conditions (VMC) and instrument meteorological conditions (IMC). VMC exist during generally fair to good weather, and IMC exist during times of rain, low clouds, or reduced visibility. IMC generally exist whenever visibility falls below 3 statute miles (SM) or the ceiling drops below 1,000 feet above ground level (AGL). The ceiling is the distance from the ground to the bottom of a cloud layer that covers more than 50% of the sky. During VMC, aircraft may operate under VFR, and the pilot is primarily responsible for seeing other aircraft and maintaining safe separation.
Types of Airspace
In the early days of aviation, aircraft only flew during VMC, which allows a pilot to maintain orientation (e.g., up/down, turning, etc.) by reference to the horizon and visual ground references. Flight through clouds (e.g., an IMC) was not possible, as the aircraft instruments of the time did not provide orientation information, and thus a pilot could easily lose orientation and control of the aircraft. In a visual-only airspace environment, it was possible to see other aircraft and avoid a collision—and thus maintain aircraft separation. Flight through clouds became possible with the use of gyroscopic flight instruments. Because it is not possible to see other aircraft in the clouds, ATC was established to coordinate aircraft positions and maintain separation between aircrafts. Today, maintaining separation between VFR and IFR air traffic is still a fundamental mission of ATC. The evolution of the National Airspace System (NAS), and existing ATC procedures, can be directly tied to this requirement to maintain separation between aircrafts.
Airspace Classifications
Aircraft operating under VFR typically navigate by orientation to geographic and other visual references. During IMC, aircraft operate under IFR; the ATC exercises positive control (e.g., separation of all air traffic within designated airspace) over all aircrafts in controlled airspace, and the ATC is primarily responsible for aircraft separation. Aircraft operating under IFR must meet minimum equipment requirements. Pilots must also be specially certified and meet proficiency requirements. IFR aircraft fly assigned routes and altitudes, and use a combination of radio navigation aids (NAVAIDs) and vectors from ATC to navigate.
Aircraft may elect to operate IFR in VMC; however, the pilot, and not ATC, is primarily responsible for seeing and avoiding other aircraft. The majority of commercial air traffic (including all air carrier traffic), regardless of weather, operate under IFR as required by Federal Aviation Regulations. In an effort to increase airport capacity, ATC can allow IFR aircraft to maintain visual separation when weather permits.
The FAA has designated six classes of airspace, in accordance with International Civil Aviation Organization (ICAO) airspace classifications. Airspace is broadly classified as either controlled or uncontrolled. Airspace designated as Class A, B, C, D, or E is controlled airspace. Class F airspace is not used in the United States. Class G airspace is uncontrolled airspace. Controlled airspace means that IFR services are available to aircraft that elect to file IFR flight plans; it does not mean that all flights within the airspace are controlled by ATC. IFR services include ground-to-air radio communications, navigation aids, and air traffic (i.e., separation) services. Aircraft can operate under IFR in uncontrolled airspace; however, the aircraft cannot file an IFR flight plan for operation in uncontrolled airspace, and IFR services are not necessarily available. Controlled airspace is intended to ensure separation of IFR aircrafts from aircrafts using both IFR and VFR.
The FAA airspace classifications are as follows:                Class A Class A airspace encompasses the en route, high-altitude environment used by aircraft to transit from one area of the country to another. All aircraft in Class A must operate under IFR. Class A airspace exists within the United States from 18,000 feet mean sea level (MSL) to and including 60,000 feet MSL.        Class B All aircraft, both IFR and VFR, in Class B airspace are subject to positive control from ATC. Class B airspace exists at 29 high-density airports in the United States for of managing air traffic activity around these airports. It is designed to regulate the flow of air traffic above, around, and below the arrival and departure routes used by airline carriers' aircrafts at major airports. The ATC can manage aircraft in and around the immediate vicinity of an airport. Aircrafts operating within this area are required to maintain radio communication with the ATC. No separation services are provided to VFR aircraft.        Class C Class C airspace is defined around airports with airport traffic control towers and radar approach control. It normally has two concentric circular areas with a diameter of 10 and 20 nautical miles. Variations in the shape are often made to accommodate other airports or terrain. The top of Class C airspace is normally set at 4,000 feet AGL. The FAA has established Class C airspace at approximately 120 airports around the country. Aircraft operating in Class C airspace must have specific radio and navigation equipment, including an altitude encoding transponder, and must obtain ATC clearance. VFR aircraft are only separated from IFR aircraft in Class C airspace (i.e., ATC does not separate VFR aircraft from other VFR aircraft, as this is the respective pilot's responsibility).        Class D Class D airspace is normally a circular area with a radius of five miles around the primary airport. This controlled airspace extends upward from the surface to about 2,500 feet AGL. When instrument approaches are used at an airport, the airspace is normally designed to encompass the aircraft flight control procedures.        Class E Class E airspace is a general category of controlled airspace that is intended to provide air traffic service and adequate separation for IFR aircraft from other aircraft. Although Class E is controlled airspace, VFR aircraft are not required to maintain contact with ATC, but are only permitted to operate in VMC. In the eastern United States, Class E airspace generally exists from 700/1200 feet AGL to the bottom of Class A airspace at 18,000 feet MSL. It generally fills in the gaps between Class B, C, and D airspace at altitudes below 18,000 feet MSL. Federal Airways, including Victor Airways, below 18,000 feet MSL are classified as Class E airspace.        Class F Not Applicable within United States        Class G Airspace not designated as Class A, B, C, D, or E is considered uncontrolled, Class G, airspace. ATC does not have the authority or responsibility to manage of air traffic within this airspace. In the Eastern U.S., Class G airspace lies between the surface and 700/1200 feet AGL.        
There are also many types and areas of special use airspace administered by the FAA:                Prohibited Areas where, for reasons of national security, the flight of an aircraft is not permitted are designated as prohibited areas. Prohibited areas are depicted on aeronautical charts. For example, a prohibited area (P-56) exists over the White House and U.S. Capitol.        Restricted In certain areas, the flight of aircraft, while not wholly prohibited is subject to restrictions. These designated often have invisible hazards to aircraft, such as artillery firing, aerial gunnery, or guided missiles. Aircraft operations in these areas are prohibited during times when it is “active.”        Warning A warning area contains many of the same hazards as a restricted area, but because it occurs outside of U.S. airspace, aircraft operations cannot be legally restricted within the area. Warning areas are typically established over international waters along the coastline of the United States.        Alert Alert areas are shown on aeronautical charts to provide information of unusual types of aerial activities such as parachute jumping areas or high concentrations of student pilot training.        Military Operations Area Military operations areas (MOA) are blocks of airspace in which military training and other military maneuvers are conducted. MOA's have specified floors and ceilings for containing military activities. VFR aircraft are not restricted from flying through MOAs while they are in operation, but are encouraged to remain outside of the area.        
Automated Dependent Surveillance-Broadcast (ADS-B) is a next generation surveillance technology incorporating both air and ground aspects and can provide the ATC with a more accurate information of the aircraft's three-dimensional position in the en route, terminal, approach, and surface environments. It has been shown to be an efficient and effective mechanism to replace the classic radar environment currently in use.
High level features of ADS-B include:                Automatic—properly-equipped aircraft automatically report their position, without need for a radar interrogation        Dependent—ADS-B depends on aircraft having an approved WAAS GPS on board and an ADS-B Out transmitter        Surveillance—it is a surveillance technology that allows ATC to watch airplanes move around        Broadcast—aircraft broadcast their position information to airplanes and ATC        
ADS-B doesn't need radar to work properly, but it will uses a network of ground stations to receive aircraft reports and send them back to ATC. These stations also transmit weather and traffic information back up to properly-equipped aircraft. This network currently consists of over 400 stations.
ADS-B is automatic because no external interrogation is required. It is dependent because it relies on onboard position sources and broadcast transmission systems to provide surveillance information to ATC and other users, such as ATC and nearby aircraft and pilots.
ADS-B is made up of two main parts: ADS-B Out and ADS-B In. ADS-B Out is of interest to controllers, while ADS-B In is mostly of interest to pilots. ADS-B Out is a surveillance technology for tracking aircraft—it's what ATC needs to manage traffic. It reports an aircraft's position, velocity, and altitude once per second. This transmission is received by ATC and nearby aircraft and this data makes up the equivalent of a radar display. Most aircraft will be required to have ADS-B Out by the year 2020. ADS-B In allows an aircraft to receive transmissions from ADS-B ground stations and other aircraft. Final ADS-B Out rules were finalized in 2011. All aircraft will be required to have ADS-B Out equipment to fly in Class A, B and C airspace, plus Class E airspace above 10,000 feet but not below 2,500 feet, by 2020.
The aircrafts forms the airborne portion of the ADS-B system as the aircrafts provide ADS-B information in the form of a broadcast of its identification, position, altitude, velocity, and other information. The ground portion of the ADS-B system consists of ADS-B ground stations, which receive such broadcasts from the aircrafts and direct them to ATC automation systems for presentation on a controller's display. Aircrafts that are equipped with ADS-B IN capability can also receive these broadcasts and display the information to improve the pilot's situation awareness of other traffic.
Security Issues
Since UAVs typically operate via digital wireless signals, the possibility exists for a malicious individual, bot, UAV or similar device, to wirelessly install UAV malware, or exploit software, and backdoor software that exploits (and overrides, or hacks into) the manufacturers intended operating software. UAVs can easily be identified via their radio frequency signals emitting from their transmitter. One such company, Domestic Drone Countermeasures, LLC, provides a plurality of sensor equipment that, when positioned in an area of interest, create a custom wireless mesh network among its sensors, to detect a UAVs' location using triangulation.
UAVs are capable of operating without RF communications (also “links” herein), or lost or jammed links. Typically, a flight plan is downloaded into the UAV's computing system that provides all required navigation data. These UAVs use the navigation data to operate an autopilot on the UAV, thus negating the requirement for constant radio communication between a UAV and its pilot or other navigation controller. In order to detect these types of UAV flights, one company, Droneshield, has a patent-pending acoustic detection technology to detect UAVs without RF links, such as those that operate on autopilot. Typical maximum range is on the order of 200 feet with low-wind conditions. The technology includes a database of common UAV acoustic signatures, to reduce the likelihood of generating false alarms, such as those from lawn mowers and leaf blowers.
Defense contractor, Israel Aerospace Industries, is designing a radar truck that specifically looks for UAV signatures. The U.S. Air Force Joint Surveillance Target Attack Radar System (JSTARS) is being mounted on a test jet for counter-UAV exercises.
A. Moses, M. J. Rutherford, and K. P. Valavanis, individuals at the University of Denver, Colo., have authored a 2011 paper that proposes means to detect miniature Air vehicles (<25 kg rotorcraft): “Radar-Based Detection and Identification for Miniature Air Vehicles,” herein incorporated by reference. This paper proposes modifying a light weight X band (10.5 GHz) radar system to scan for Doppler signatures of small air vehicles (UAVs or drones).
W. Shi, et al, with the MITRE Corp., wrote a paper, “Detecting, Tracking and Identifying Airbrone Threats with Netted Sensor Fence,” herein incorporated by reference, using a low-power pulse-Doppler radar “fence,” with a range of about 5 km. Other methods explored included IR detection with optical sensors, and acoustic sensors.
A paper in 2011 by M. Peacock, et al, with the ECU Security Research Institute (Australia), provided early details of wireless signal identification and control exploitation: “Towards Detection and Control of Civilian Unmanned Aerial Vehicles,” herein incorporate by reference.
In November, 2014, the DoD issued an RFI called project Thunderstorm, with the intent to invite technologists to respond to the need to detecting and countering Commercial Off The Shelf (COTS) based UAV (Unmanned Aerial systems) with potential WMD payloads (Spiral 15-3b). Demonstrations are expected to be performed in Camp Shelby, Miss. in 2Q2015. Pennsylvania State University's Applied Research Laboratory (ARL/PSU) will act as the demonstration director for spiral 15 demonstrations.
The DoD is interested in remote detection ranges up to 1,000 feet. Beyond detection of target UAVs, the need exists to detect and identify chemical and/or biological agents and weapons. Chemical agents include biological warfare agents (e.g., Sarin, and vegetative cells, spores, and standard G, H and V series chemical agents), and radiological and nuclear materials The detectors are expected to be mounted on search UAVs, capable of 30 minute flights, an autonomous operation (takeoff, surveillance and landing), as well as utilizing and/or detecting wireless systems such as Wi-Fi and cellular radio system infrastructure. Location accuracy should be within +/−10 meters position, and 1 meter accuracy in altitude.
In the case of RF wireless controlled UAVs, malicious UAV software installations can occur quickly and without the knowledge or permission of UAV owner/manufacturer. In an area of interest, wireless signals are monitored to find UAV-specific characteristics (typically MAC addresses). Using standard wireless protocols and malware exploit software, wireless signal control is re-directed to a wireless, rogue controller system that assumes control of the targeted UAV. Once wireless signal control is achieved, other backdoor capabilities include access to various UAV, or quadcopter sensors, video feeds and control subsystems.
A specific UAV malware example is “SkyJack,” provided on the Internet by Samy Kamkar (India). Skyjack is primarily a Perl application running on a Linux machine that also includes “aircrack-ng”. This program, in communication with a wireless adapter such as the Alfa AWUS036H wireless card, listens to Wi-Fi signals and identifies wireless networks and clients. UAV manufacturers identities can be determined via their MAC addresses and the IEEE Registration Authority OUI. Once the UAV wireless network has been identified, such as Parrott, the clients or UAVs, can be compromised. The program “aireplay-ng,” in addition to the wireless card, supports raw packet injection. This capability is used to deauthenticate the true owner of the UAV being targeted. Another program, “node-ar-drone,” along with the wireless card, reauthenticates the targeted UAV with the wireless card associated with the malicious controller system, thus reconnecting it to the now free Parrot AR UAV as its new owner. A Java script called “node.js,” with the wireless card, is then invoked that assumes control of the compromised UAV.
In addition to control, video and sensor data can be received by the malicious system. After the UAV is hijacked, backdoor payload program or botnet can be installed into the UAV's software operating system, such as Rahul Sasi's “Maldrone.” Maldrone provides access to sensors via serial ports, such as: (a) inertial measurements unit (IMU), (b) 6 Degree Of Freedom gyroscope, (c) 3 DOF magnetometer, (d) ultrasound sensor (used for low altitude measurements), (e) a pressure sensor (altitude measurement at all altitudes, and (f) a GPS sensor.
An outline of the steps that Maldrone executes includes:
    Step 1: Kills the drone program, e.g., program. elf    Step 2: Setup a proxy serial port for navboard and others.    Step 3: Redirect actual serial port communication to fake ports    Step 4: Patch program. elf and make it open our proxy serial ports.    Step 5: Maldrone communicates to serial ports directly
Now all serial communication to navigation control board goes via Maldrone. Maldrone, also termed a botnet, can intercept and modify UAV data on the fly. The botnet uses the wireless UAV connection to connect to a botserver, operated by a botmaster. One wireless adapter useful in this regard is the Edimax EW-7811Un wireless USB adapter, which allows Skyjack to launch its own network of botserver(s).
A botmaster is a person who operates the command and control of botnets for remote execution. Botnets are typically installed on compromised machines via various forms of remote code installations. Detecting botnets and their servers are often difficult, and identities are hidden via proxies. TOR shells disguise their IP address, thus precluding detection by authorized investigators and law enforcement.
The botmaster can next create a man-in-the-middle attack, by re-establishing a wireless signal authorization request sent to the original UAV owner's wireless controller. Once wireless authentication is achieved, the UAV's botnet, in conjunction with the botserver, can re-direct signals and controls messages between the UAV and the original owner's wireless control system. This procedure provides the allusion that no UAV hacking has occurred, and that no compromises are in effect.
Other types of UAV malware, such as Dongcheol Hond's HSDrone, made at SEWORKS, can spread itself automatically to an entire army of UAVs in a wireless networked area.
UAV, often being constructed using stealth materials such as graphite composites, generally evade traditional FAA area controller, X-band radar. A DJI Phantom quad-copter UAV flew successfully and without notice onto the white house property, in January of 2015. Radar systems are designed to only detect larger objects, such as missiles and airplanes, that operate at higher altitudes. In commercial UAV management, Brian Field-Elliot's PixiePath startup provides services and tools, or adapters for DJI and PIXHawk-based UAVs to send telemetry to the cloud, then waits for positioning commands, to manage whole fleets of UAVs. Dan Patt, DARPA, is interested in promoting large aircraft that could air-drop smaller UAVs.
Last year, 3D Robotics announced its Iris quadcopter UAV. Like other similar products, it can either be flown manually using radio remote control, or it can use its onboard GPS to autonomously fly between a series of preprogrammed waypoints. The company announced its successor, the Iris+, that includes a Follow Me function, which allows it to automatically fly along above a moving ground-based GPS-enabled Android device. This means that when equipped with, for example, a GoPro actioncam, the UAV can get tracking footage of a person moving around, such as cycling, skiing or surfing.